In[33]:= ContourPlot[{-y^3 + 3*y - x^3  - Range[-25, 25, 2] == 0},
{x, -4, 4}, {y, -4, 4}, Axes->True,AxesStyle->Black]
In[36]:= ContourPlot[{y^2 - 2*y - x^3  - 2*x^2 - 2*x - Range[-24, 24, 3] == 0},
{x, -3, 3}, {y, -3, 3}, Axes->True,AxesStyle->Black]
In[37]:= ContourPlot[{y^4 + 16*y + x^4  - 8*x^2 - Range[-45, 45, 15] == 0},
{x, -4, 4}, {y, -3.5, 2.5}, Axes->True,AxesStyle->Black]